Ischemic preconditioning in pigs: a graded phenomenon: its relation to adenosine and bradykinin.
Circulation
; 98(10): 1022-9, 1998 Sep 08.
Article
in En
| MEDLINE
| ID: mdl-9737523
ABSTRACT
BACKGROUND:
A threshold concept for ischemic preconditioning (IPc) has been proposed. It is unclear, however, whether IPc, above a certain threshold, is an all-or-nothing or a graded phenomenon. METHODS ANDRESULTS:
In 71 enflurane-anesthetized swine, severe left anterior descending coronary artery hypoperfusion for 90 minutes followed by 2 hours of reperfusion resulted in an infarct size (IS, by triphenyltetrazolium chloride) of 16.7+/-3.4% (SEM) of the area at risk. IPc by 2 minutes of low-flow ischemia and 15 minutes of reperfusion before the 90-minute target ischemia did not reduce IS (21.9+/-7.0%). IS was decreased to 9.0+/-2.6% (P<0.05) by 3 minutes of IPc and reduced further to 1.9+/-0.9% (P<0.05) by 10 minutes of IPc. The interstitial adenosine concentration (microdialysis, high-performance liquid chromatography) was unchanged with 2 and 3 minutes of IPc but increased with 10 minutes of IPc (by 573+/-144%). The interstitial bradykinin concentration (microdialysis, radioimmunoassay) remained unchanged with 2 minutes of IPc but increased to a similar extent with 3 minutes (by 198+/-32%) and 10 minutes (by 224+/-30%) of IPc. The IS reduction by 3 minutes of IPc was abolished by blockade of the bradykinin B2 receptor with intracoronary HOE 140 (16.6+/-4.3%) but not with intracoronary infusion of adenosine deaminase (8.4+/-2.5%, P<0.05). HOE 140, however, did not affect the IS reduction (3.5+/- 1.1%, P<0.05) by 10 minutes of IPc. Combined infusion of HOE 140 and adenosine deaminase abolished the IS reduction by 10 minutes of IPc (15.4+/-6.7%).CONCLUSIONS:
IS reduction by IPc is a graded phenomenon. Whereas bradykinin is essential during preconditioning ischemia of shorter duration, adenosine is more important during preconditioning ischemia of longer duration.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Bradykinin
/
Adenosine
/
Ischemic Preconditioning, Myocardial
/
Coronary Circulation
/
Bradykinin Receptor Antagonists
/
Hemodynamics
/
Myocardial Infarction
Limits:
Animals
Language:
En
Journal:
Circulation
Year:
1998
Document type:
Article
Affiliation country:
Germany